SIDE AIRBAG AND SIDE AIRBAG DEVICE

A side airbag that is to be inflated and deployed to a side of an occupant, includes: a first chamber that is positioned in an upper portion and is to be inflated to a side of a shoulder part of the occupant; and a second chamber that is on a lower side of the first chamber, and a thickness regulating member for reducing an inflation thickness is provided at an upper portion of a front portion of the second chamber.